Electrical control system



Oct. 9, 1934. A. HYLAND ELECTRICAL CONTROL SYSTEM Filed May 6, 1929 2 Sheets-Sheet l T531 Ila-E;

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- ELECTRICAL CONTROL SYSTEM I I Filed ma 6, 1929 2 Sheets-Sheet 2 TEE-ma \ggg ATTORNEY Patented Oct. 9, 1934 4 UNITED STATES PTTEET @FEQE to Wired Radio, lina, poration of Delaware New York, N. $1., a cor- Application May 6, 1929, Serial No. 389,905

2 Claims.

My invention relates broadly to circuit arrangements for electron discharge devices, and more specifically to electron discharge devices employed for controlling the resistance of cir- 15 cuits.

One of the objects of my invention is to provide a variable resistor employing an electron discharge device in which the variable resistance circuit is electrically isolated from other circuits associated with the electron discharge device.

Another object of my invention is to provide a variable resistance apparatus employing an electron discharge device having an electron emitting electrode, an anode and a heating electrode, in which the circuit of the heating electrode is isolated from the circuits or the electron emitting electrode and the anode.

Still another object of my invention is to provide a variable resistor employing an electron .20 discharge device for controlling the operation of circuits of other electron discharge devices.

A further object of my invention is to provide a variable resistor employing an electron discharge device for controlling the operation of cir- 'cuits of other electron discharge devices in which all of the electron discharge devices employ or are adapted to employ the same source of cathode energization supply. My invention will be more fully understood from the specification hereinafter following by reference to the accompanying drawings.

According to my invention an electron discharge device having an anode, acathode and a heating electrode which is electrically insulated from the cathode but thermally associated therer with, is employed as a continuously variable resistor. The resistance of the path between the electron emitting electrode and the anode is varied by varying the heating current flowing 40 through the heater electrode. Since the heater electrode is electrically isolated from the cathode the same source of heating current may be employed for energizing the cathode which is operatively associated with other circuits which may be at a diiierent potential. For example, where the resistor of my invention is employed to control the resistance of the grid circuit of electron discharge devices, the same source of current may be used to energize the cathodes of the resistor and the electron discharge device. Likewise the electron discharge resistor of my invention may be employed to control the anode current of electron discharge device amplifier and oscillation generator arrangements in cases where the same source of current supply is employed in energizing the cathode of the resistor as well as the other electron discharge de- Reference numeral l of Fig. l of the drawingsv designates an electron discharge device having an anode 2, a heater electrode a and an electron emitting electrode 3, which is energized thermally through the action of the heat transmitted to it from the heater electrode a. The electrode 3 and the heater electrode a are electrically isolated from each other. The heater electrode 4 may be surrounded by an insulating member of mica, quartz or similar material, the electrical insulating properties of which do not materially deteriorate as the temperature of the member is increased and the electron emitting electrode 3 may be mounted upon the exterior of the insulating in order to receive heat from the heater electrode by conduction or the electrode 3 may be supported in the vacuous space within the electron discharge device 1 adjacent to the heater electrode 4. A source 5 of heating current is cornected to the variable resistance unit 6 and the electrode 4.

In Fig. 2 is illustrated a modified form of the invention in which the electron discharge device 7 which is provided with anode 8, electron emitting electrode 9 and heater electrode 10, is energized from a source 14 of alternating current supply.

The secondary winding 12 of the transformer 11 is connected to the electrode 10 of the device 7. The primary winding 13 is connected to the variable resistance 15 14. The variable resistance units 6 and 15 illustrated in Figs. 1 and 2 are employed to control the operation of the electron discharge device resistors. The variable resistance unit 6 controls the magnitude of the current flowing through the heater electrode a and therefore controls the electron emission from the electrode 3 since this emission is proportional to the temperature of the electrode. The resistance between the electron emitting electrode and the ent upon the rate of emission from the electron emitting electrode to a large extent and is therefore controlled by the variable resistance unit. 'Where' alternating current is used to heat the heater electrode, as is the case when the circuit.-

and the source of supply.

anode is dependformer 11 for reducedto a low value by increasing '32, respectively,

arrangement illustrated in Fig. 2 is employed, a variable resistance or impedance unit, such as a variable choke coil, may be employed either in the primary or the secondary circuit of the transcontrolling the current through the heater electrode 10 and the resistance of the electron discharge device 7.

Fig. 3 of the drawings shows a circuit arrangement in which the device 16 is employed to control the anode current flowing from the source 18 through the discharge device 17. Connections are provided between the primary winding of the output transformer 19 and the electron emitting or cathode electrode 16b of device 16.

Connections are also provided between the inductance 20, which is coupled to the inductance 21, and the anode 17a of device 17. A high frequency oscillation by-pass condenser 24 is connected between the inductance 20 and the oathode 1'7c to provide a relatively low impedance path for high frequency oscillations across the output transformer 19. A variable condenser 22 is connected across the inductance 21. Connections are provided between the grid electrode 171) and the oscillatory circuit comprising condenser 22 and inductance 21. A source of potential 23 is provided to the input circuit of the device 17 for determining the operating characteristics of the electron discharge device 1'7. The primary winding of the transformer 25 is connected to the source of alternating current supply 26. A variable resistance unit 27 is connected to j the heater electrodes 16c and 17d of the electron discharge devices 16 and 17 for varying the current flowing through the circuits of these electrodes from the secondary winding of the transformer 25. Separate variable resistance units may be employed for varying the current through the electrodes 16c and 17d individually. A direct current source of energize the heater electrodes in place of the alternating current supply. In case a direct culrent source is employed the transformer 25 is, of course, eliminated. The regenerative condition of the circuit of the electron discharge device 17 is controlled by controlling the anode current-flowing from the source 18 through the action of the device 16.

When it is desired to generate high frequency oscillations in the circuits of the device 1'7 for the purpose of receiving and observing signals of, for example, the continuous wave undamped type, the resistance of the device 16 is the current through the electrode 160 so that the electron emission from the electrode 161) increases.

The application of the resistor of this invention to the control of the various circuits of amplifying systems is further illustrated in Fig. 4 of the drawings wherein electron discharge device 28, having anode 28a, cathode 28c and cathode energizing electrode 282), is employed vto control the resistance of the grid circuit of the'electron discharge device 29 which is coupled to the circuits of the antenna 33 and the ground '34 through the transformer 35. The anode electrodes 30a and 32a of the devices 30 and which are similar to device 28, are connected to the source 36 of current supply for controlling the'anode current of the discharge devices 29 and 31. Connections are also provided'between the cathodes 30c and 320 of the devices 30 and'32, respectively, and the primary winding of transformer 3'7 and the choke.

supply may be employed to eliminated. Where it is desired, the alternating current source may also be replaced by a direct current source. Variable resistance units 41, a2 and 43 are employed for varying the current through the heater electrodes of the electron discharge devices 28, 3G and 32, respectively, so that the resistance between the electron emitting electrodes and the anodes of these devices may be readily controlled. By varying the value of the resistance unit 41 the resistance of the device 28, which acts as a grid to filament resistor for the device 29, is varied. Likewise by varying the resistance of the resistance units 42 and 43 the anode current of the discharge devices 29 and 31 is varied. may be employed as an output control for the amplifying system independently of the other.

Variable resistance units made up of electron discharge devices, such as device 1, may be employed in the anode and grid circuits of transmitters as well as in receiver circuits.

While I have described my invention in several of its embodiments it is to be understood that modifications thereof may be made without departing from the spirit and scope of this invention and that therefore I do not desire to limit this invention to the exact details as set forth in the fcregoin specification except as defined by the appended claims.

What I claim as new Letters latent of the United States is as follows:

1. In an electricalcontrol system, an electron tube having an anode, a control electrode, a cathode and a cathode heater element; in com- Either one of the devices 30 and 32 and desire to secure 051 bination with input and output circuits for said; 20

cuit and a cathode heater element electrically insulated from said cathode; and means for varying the 'flow of current through the last said heater element whereby the resistance of said second electron tube is varied.

2. In an electrical control system, an electron tube having at least three electrodes, namely, an anode, a control electrode and a cathode; an electron tube having at least two electrodes, namely, an anode and a cathode; cathode heator elements for each of saidcathodes, said elements being thermally related to, while electrically insulated from, said cathodes, a source of heating current common to each of said cathode heater elements, an input and an output circuit for the first said electron tube, said output circuit including a space path through the second said electron tube, and means for varying the amplitude of said heating current whereby the resistance of said space path is varied and the potential applied between the cathode and the. anode of the first said tube is correspondingly controlled.

LAWRENCE A. HYLAND. 

